1. Field of the Invention
The present invention relates to a sound field control apparatus, a signal processing apparatus, and a sound field control program which generate reflected sound signals from picked-up sound signals output from a plurality of microphones installed in a room, and outputs output sounds (output sounds) based on the generated reflected sound signals from a plurality of speakers installed in the room, thereby enhancing the feeling of reverberation and expansion of the room itself, as well as a signal processing program.
2. Description of the Related Art
Conventionally, as an example of a sound field control apparatus which enhances the feeling of reverberation and expansion of a hall or a room, a sound field control apparatus employing an acoustic feedback system has been known (refer to Japanese Laid-Open Patent Publication (Kokai) No. 2001-228867, for example). This sound field control apparatus is constructed such that speakers and microphones are installed at a suitable distance from each other in a hall or a room, and sounds picked up by the microphones are supplied to an FIR (Finite Impulse Response: non-recursive type) filter via a head amplifier to generate reverberation signals which are primarily composed of initial reflected sound signals. The generated reverberation signals are amplified and reproduced via the speakers, and the reproduced sounds are picked up again by the microphones. By repeating this sequence, the sound field control apparatus causes increase in the level of sound pressure to enhance the feeling of sound volume, extension of the reverberation time to enhance the feeling of reverberation, and intensification of sideway reflected sound energy to enhance the feeling of expansion.
The above conventional sound field control apparatus is constructed such that the number of microphones and the number of speakers are the same, but actually, the number of speakers is increased or decreased depending on the dimensions of the installation space such as a hall or a room. For this reason, there may be a case where the number of speakers is considerably larger than the number of microphones. In this case, the number of outputs to the speakers from the conventional sound field control apparatus is fixed, and hence, if the number of outputs is small, the sound field control apparatus is not suitable for a large hall, and if the number of outputs is large, a large number of outputs are not used in a small room.
Also, it can be envisaged that the number of outputs is increased by adding sound field control apparatuses, but in this case, when the user selects a desired sound field pattern, sound field control data for the selected sound field pattern must be transferred to the added sound field control apparatuses, and therefore, it takes a lot of time to switch sound field control data among the plurality of sound field control apparatuses.
Similarly, in the case where the number of outputs is increased by adding sound field control apparatuses, if devices sharing functions constitute one sound field control apparatus, the sound field control apparatus is comprised of a plurality of types of devices having different constructions adapted to the respective shared functions. Thus, in case that any of the devices fails, a device adapted to a function of the failed device must be prepared in advance for replacement, and therefore it is necessary to prepare a plurality of types of spare devices in advance.
Further, when installing the sound field control apparatus, sound field control data for obtaining a desired sound field pattern to be set in the sound field control apparatus is adjusted according to a space where the sound field control apparatus is installed by an installer, so that plural pieces of sound field control data suitable for the space are stored in a nonvolatile memory such as a flash memory in the sound field control apparatus. The user cannot change the sound field control data. Thus, when the sound field control apparatus fails, even if the failed sound field control apparatus is replaced by a new sound field control apparatus of the same type, sound field control data stored in the new sound field control apparatus is not suitable for the space, and hence it is impossible to properly operate the new sound field control apparatus. For this reason, the installer needs to back up sound field control data which has been adjusted in installation for recovery from failure, and write the backed-up sound field control data in a nonvolatile memory of a new sound field control apparatus in case of a failure. It is necessary to use a personal computer for writing this backup data, and to carry this personal computer which stores the backed-up control data to the place of the failure.